TW201304239A - Lithium-ion electrochemical cells that include fluorocarbon electrolyte additives - Google Patents

Abstract

Lithium-ion electrochemical cells are provided that include a positive electrode that includes a lithium metal oxide or a lithium metal phosphate, a negative electrode capable of intercalating or alloying with lithium, and an electrolyte that includes an additive. The additive includes a multifunctional anion that has the formula, X-SO2-Rf'-SO2-Y, wherein X and Y are, independently, either O- or RfSO2N-, Rf is a straight or branched fluoroalkyl moiety having from 1 to 6 carbon atoms, and can, optionally, contain one or more in-chain heteroatoms, wherein Rf' is a straight or branched chain or cyclic fluoroalkylene having from 1 to 10 carbon atoms and can, optionally, contain one or more in-chain heteroatoms, and wherein both Rf and Rf' have a maximum of 20% non-fluorine substituents. The provided additives can improve the performance, hydrolytic stability, and thermal stability of the provided electrochemical cells.

Description

Lithium ion electrochemical cell including fluorinated carbon electrolyte additive

This invention relates to lithium ion electrochemical cells and additives that improve electrolyte performance.

Although commercial lithium-ion batteries (LIB) perform satisfactorily in most home electronics applications, currently available LIB technology does not meet hybrid electric vehicles (HEV), plug-in hybrid electric vehicles (PHEF) or pure electric Some of the more demanding performance goals of the vehicle (EV). In particular, the currently available LIB technology does not meet the 10 to 15 year calendar life requirements set by the Next Generation Vehicle Generation Development Program (PNGV). The most widely used LIB electrolytes have limited thermal stability and high pressure stability. Thermal degradation and electrochemical degradation of electrolytes are considered to be the main reason for the decrease in the performance of lithium-ion batteries over time. Many of the performance and safety issues associated with contemporary lithium-ion batteries are direct or indirect results of improper reactions between the electrolyte and the highly reactive positive or negative electrode. These reactions result in reduced cycle life, capacity decay, gas production (which can cause battery bleed), impedance growth, and a decrease in rate capability. In general, driving the electrodes to a greater voltage extreme or exposing the battery to higher temperatures can accelerate such improper reactions and amplify related problems. Under extreme abuse conditions, uncontrolled exothermic heat can cause thermal runaway and catastrophic disintegration of the battery.

Stabilizing the electrode/electrolyte interface to control and minimize these undesirable reactions and improve the cycle life and voltage and temperature performance limits of Li-ion batteries The key to the system. Electrolyte additives designed to selectively react with the electrode surface, bind to the electrode surface, or self-organize at the electrode surface to passivate the interface represent one of the simplest and potentially most cost effective methods to achieve this goal. There is sufficient evidence to show that common electrolyte solvents and additives (such as ethyl carbonate (EC), ethylene carbonate (VC), 2-fluoroextension ethyl ester (FEC) and lithium bis(oxalate) borate (LiBOB) are negative. Effect of Stability of Electrode SEI (Solid Electrolyte Interface) Layer There is evidence that carbonic acid vinyl ester (VC) and lithium bis(oxalate) borate (LiBOB) react, for example, on the surface of the anode to produce a more stable solid electrolyte interface (SEI). Stabilizing SEI and inhibiting harmful thermal reactions and redox reactions that can cause electrolyte degradation at the electrode interface (cathode and anode) will prolong the life and cycle life of LIB and increase its thermal stability.

Lithium bis(trifluoromethanesulfonyl)imide (available from HQ-115 from 3M, St. Paul, MN) is commonly used as an electrolyte additive in commercial lithium ion electrochemical cells to improve performance. Lithium bis(trifluoromethanesulfonyl)imide improves the cycle life of graphite/LiCoO ₂ cells at high temperatures. Similar results were obtained in a graphite/Li mixed metal oxide battery. The cycle life improvement achieved by the addition of lithium bis(trifluoromethanesulfonyl)imide is associated with reduced cell impedance. Lithium bis(trifluoromethanesulfonyl)imide also reduces the gas production of the negative electrode and prevents short circuits in the presence of a single layer of polyethylene separator under high temperature float test conditions. Therefore, the use of lithium bis(trifluoromethanesulfonyl)imide as an additive in a standard electrolyte for lithium ion electrochemical cells has improved battery life and safety.

However, there is a need to improve the high temperature performance and stability of lithium ion batteries. Properties (eg, >55 ° C) provide electrolyte stability at high pressures (eg, >4.2 V) to achieve increased energy density and enable the use of electrolyte additives for high voltage electrodes. A novel type of fluorinated compound is provided that can serve as an additive to the electrolyte of a lithium ion electrochemical cell. Performance benefits can be provided in lithium ion batteries when such compounds are used in electrolytes at relatively low loadings compared to conventional additives. Novel fluorinated additives contain two or more pendant sulfonate groups or sulfonium imino groups, and their unusual efficacy at low loadings is expected to reduce the total additive cost per cell. Reducing material costs is important for the growth of lithium-ion batteries in electronic applications and is critical to the success of this technology in the automotive field.

In one aspect, a lithium ion electrochemical cell is provided comprising a positive electrode comprising a lithium metal oxide or a lithium metal phosphate, a negative electrode capable of intercalating lithium or alloying with lithium, and an electrolyte comprising an additive, wherein the additive A polyfunctional anion having the formula: X-SO ₂ -R _f '-SO ₂ -Y, wherein X and Y are independently O ^- or R _f SO ₂ N ^- , wherein R _f is from 1 to 6 carbons a linear or branched fluoroalkyl moiety of an atom and optionally one or more interchain heteroatoms selected from the group consisting of nitrogen, oxygen, and combinations thereof, wherein R _f ' is a straight or branched chain having from 1 to 10 carbon atoms The chain or cyclic fluoroalkyl moiety and optionally contains one or more intrachain oxygen atoms, and wherein both _Rf and _Rf ' have up to 20% non-fluorine substituents. In some embodiments, the polyfunctional anion is a divalent anion such as a disulfonate or a disulfonimide anion. In some embodiments, the polyfunctional anion is perfluorinated.

In another aspect, a method of stabilizing a lithium ion electrochemical cell is provided, comprising providing a negative electrode and electrolyte having a lithium metal oxide positive electrode or a lithium metal phosphate positive electrode, capable of intercalating lithium or forming an alloy with lithium a lithium ion electrochemical cell to which a polyfunctional anion having the chemical formula X-SO ₂ -R _f '-SO ₂ -Y is added, wherein X and Y are independently O ^- or R _f SO ₂ N ^- , wherein R _f is a linear or branched fluoroalkyl moiety of 1 to 6 carbon atoms and optionally one or more interchain heteroatoms selected from nitrogen, oxygen or a combination thereof, wherein R _f 'is from 1 to 10 carbon atoms A straight or branched chain or cyclic fluoroalkyl group optionally containing one or more intrachain oxygen atoms, and wherein both R _f and R _f ' have up to 20% non-fluorine substituents.

In another aspect, a lithium ion electrochemical cell is provided comprising a positive electrode comprising a lithium metal oxide or a lithium metal phosphate, a negative electrode capable of intercalating lithium or alloying with lithium, and a solid polymer electrolyte comprising an additive Wherein the additive comprises a polyfunctional anion having the formula R _f SO ₂ -N ^- -SO ₂ -(CF ₂ ) _n -SO ₂ -N ^- -SO ₂ R _f wherein R _f is from 1 to 6 carbon atoms a straight or branched fluoroalkyl moiety and optionally one or more interchain heteroatoms selected from nitrogen, oxygen or a combination thereof, wherein R _f ' is a straight or branched chain having from 1 to 10 carbon atoms Or cyclic fluoroalkylene and optionally containing one or more intrachain oxygen atoms, and wherein both _Rf and _Rf ' have up to 20% non-fluorine substituents.

In the present invention, the term "active material" or "electrochemically active material" is used interchangeably and refers to a material that can reversibly react with lithium; "capable of intercalating lithium" means an electrochemically active material that can reversibly react with lithium; "Intrachain heteroatoms" means bonds other than carbon in the carbon chain (eg, oxygen and nitrogen) An electrode that is bonded to a carbon atom to form a carbon-heteroatom-carbon chain; a "negative electrode" refers to an electrode that undergoes electrochemical oxidation and delithiation during discharge (often referred to as an anode); and a "positive electrode" refers to an electrode Electrodes that undergo electrochemical reduction and lithiation during discharge (often referred to as cathodes); the above [invention] is not intended to describe each of the disclosed embodiments of each of the embodiments of the present invention. The following [Brief Description] and [Embodiment] more specifically illustrate the illustrative embodiments.

In the following description, reference is made to the accompanying claims, It is to be understood that other embodiments may be contemplated and formed without departing from the scope of the invention. Therefore, the following embodiments are not to be considered as limiting.

All numbers expressing feature sizes, quantities, and physical properties used in the specification and claims are to be understood as being modified by the term "about" in any case unless otherwise indicated. Accordingly, the numerical parameters set forth in the foregoing specification and the appended claims are approximations, unless otherwise indicated, which may be modified by the skilled person in the art. The use of numerical ranges by endpoints includes all numbers within the range (eg, 1 to 5 includes 1, 1.5, 2, 2.75, 3, 3.80, 4, and 5) and any range within the range.

A lithium ion electrochemical cell is provided that includes at least one positive electrode, at least one negative electrode, and an electrolyte. The electrochemical cell provided can also include at least one separator. The positive electrode and the negative electrode may include a current collector, an active material, a conductive diluent, and a binder. A lithium ion electrochemical cell is provided comprising an additive in an electrolyte comprising a polyfunctional anion having the formula: X-SO ₂ -R _f '-SO ₂ -Y, (I) wherein X and Y are independently O ^- or R _f SO ₂ N ^-, wherein R _f is a straight chain having from 1 to 6 carbon atoms or a branched fluoroalkyl moiety, and R _f 'is a linear or branched chain of 1 to 10 carbon atoms or a ring a fluorine-like alkyl moiety. _Rf may optionally contain one or more intrachain heteroatoms selected from nitrogen, oxygen or a combination thereof, and _Rf ' may optionally contain one or more intrachain oxygen atoms. Both R _f and R _f ' may be partially fluorinated as appropriate, with up to 20% of the non-fluorine substituent being hydrogen. The electrolyte may also include other additives as will be described later. In some embodiments, the polyfunctional anion is a divalent anion. In some embodiments, the polyfunctional anion is perfluorinated.

A lithium ion electrochemical cell is provided that includes a positive electrode that includes a lithium metal oxide or a lithium metal phosphate. The positive electrode can be in the form of a complex. The positive composite electrode provided includes a lithium metal oxide or lithium metal phosphate active material. The metal may be one or more transition metals, which may include, for example, one or more metals selected from the group consisting of manganese, molybdenum, niobium, tungsten, niobium, iron, copper, titanium, vanadium, chromium, nickel, cobalt, zirconium, hafnium or Its combination. Examples of materials suitable for the positive electrode include LiV ₃ O ₈ , LiV ₂ O ₅ , LiCo _0.2 Ni _0.8 O ₂ , LiNi _0.33 Mn _0.33 Co _0.33 , LiNi _0.5 Mn _0.3 Co _0.2 , LiNiO ₂ , LiFePO ₄ , LiMnPO ₄ , LiCoPO ₄ LiMn ₂ O ₄ and LiCoO ₂ ; a positive electrode material comprising a mixed metal oxide of cobalt, manganese and nickel, such as U.S. Patent Nos. 6,964,828, 7,078,128 (both to Lu et al.) and 6,660,432 (Paulsen) The positive electrode material described in et al.; and the nanocomposite positive electrode material, such as the nanocomposite positive electrode material discussed in U.S. Patent No. 6,680,145 (Obrovac et al.).

The lithium ion electrochemical cell provided includes a negative electrode capable of intercalating lithium or alloying with lithium. The lithium metal oxide positive electrode described above can be combined with an anode and an electrolyte to form a lithium ion electrochemical cell or a battery pack from two or more electrochemical cells. Suitable anode examples can be made from a composition comprising lithium, a carbonaceous material, a bismuth alloy composition, a tin alloy composition, and a lithium alloy composition. Exemplary carbonaceous materials can include synthetic graphite, such as mesocarbon microbead (MCMB) (available from Osaka Gas Co., Japan), SLP30 (available from TimCal Ltd., Bodio, Switzerland), natural stone. Ink and hard carbon. Suitable anode materials may also include alloy powders or films. The alloys may include electrochemically active components such as antimony, tin, aluminum, gallium, indium, lead, antimony, and zinc, and may also include electrochemically inactive components such as iron, cobalt, transition metal tellurides, and transitions. Metal aluminide. Suitable alloy anode compositions may include tin or tantalum alloys such as Sn-Co-C alloys, Si ₆₀ Al ₁₄ Fe ₈ TiSn ₇ Mm ₁₀ and Si ₇₀ Fe ₁₀ Ti ₁₀ C ₁₀ , where Mm is a mixed rare earth metal (Mischmetal) ) (alloy of rare earth elements). The metal alloy composition used to make the anode may have a nanocrystalline or amorphous microstructure. The alloys can be made, for example, by sputtering, ball milling, rapid quenching, or other means. Suitable anode materials also include metal oxides such as Li ₄ Ti ₅ O ₁₂ , WO ₂ and tin oxide. Other suitable anode materials include tin-based amorphous anode materials such as the tin-based amorphous anode materials disclosed in U.S. Patent No. 7,771,876 (Mizutani et al.).

Exemplary niobium alloys useful in making a suitable anode include from about 65 mol% to about 85 mol% Si, from about 5 mol% to about 12 mol% Fe, from about 5 mol% to about 12 mol% Ti, and about 5 mol%. Composition to about 12 mol% C. Other examples of suitable niobium alloys include: compositions comprising ruthenium, copper, and silver or silver alloys, such as those discussed in U.S. Patent Application Publication No. 2006/0046144 (Obrovac et al.); Multiphase ruthenium containing electrodes as described in U.S. Patent No. 7,498,100 (Christensen et al.); bismuth alloys containing tin, indium and lanthanides, lanthanides or lanthanum, such as U.S. Patent Nos. 7,767,349, 7,851,085 and 7,871,727 a bismuth alloy as described in Obrovac et al.; an amorphous alloy having a high bismuth content, such as the amorphous alloy discussed in U.S. Patent No. 7,732,095 (Christensen et al.); and other powders for the negative electrode Materials such as the powder materials discussed in U.S. Patent Application Publication No. 2007/0269718 (Krause et al.) and U.S. Patent No. 7,771,861 (Krause et al.). The anode can also be made from a lithium alloy composition, such as an anode of the type described in U.S. Patent Nos. 6,203,944 and 6,436,578 (both to Turner et al.) and U.S. Patent No. 6,255,017 (Turner).

A lithium ion electrochemical cell is provided that includes an electrolyte. Any suitable electrolyte can be included in the lithium ion battery. The electrolyte can be in the form of a solid polymer or a liquid or gel (a combination of solid polymer plus liquid), but is typically a liquid or gel electrolyte. Exemplary solid electrolytes include dry polyelectrolytes such as polyethylene oxide, polytetrafluoroethylene, polyvinylidene fluoride, fluorocopolymers, polyacrylonitrile, or combinations thereof. Exemplary electrolyte gels include U.S. Patent Nos. 6,387,570 (Nakamura et al.) and 6,780,544 (Noh). The electrolyte gel described in the above. Exemplary liquid electrolytes include ethyl carbonate, dimethyl carbonate, diethyl carbonate, propyl carbonate, γ-butyrolactone, tetrahydrofuran, 1,2-dimethoxyethane, dioxolane , 4-fluoro-1,3-dioxol-2-one or a combination thereof. The electrolyte may also include ethyl methyl carbonate, ethylene carbonate, substituted ethylene carbonate, and halogenated cyclic carbonate such as 2-fluoroethyl carbonate.

The electrolyte may include a charged lithium electrolyte salt such as LiPF ₆ , LiBF ₄ , LiClO ₄ , bis(oxalic acid) lithium borate, LiN(SO ₂ CF ₃ ) ₂ , LiN(SO ₂ CF ₂ CF ₃ ) ₂ , LiAsF ₆ , LiC(SO ₂ CF ₃ ) ₃ , LiN(SO ₂ F) ₂ , LiN(SO ₂ F)(SO ₂ CF ₃ ), LiN(SO ₂ F)(SO ₂ C ₄ F ₉ ), and combinations thereof.

The electrolyte of the provided lithium ion electrochemical cell comprises a fluorinated polyfunctional anion. In one embodiment, the anion has the formula X-SO ₂ R _f '-SO ₂ -Y, wherein X and Y are independently O ^- or R _f SO ₂ N ^- . Usually X is the same as Y. In some embodiments where X and Y are the same, depending on the branching chain in the -R _f '- moiety, the polyfunctional anion may be a polyfunctional sulfonate anion such as a disulfonate when X and X are O ^- a trisulfonate, a tetrasulfonate or even a hexasulfonate anion, or a polyfunctional disulfonimide anion such as disulfonimide, trisulfonimide when X and Y are R _f SO ₂ N ^- Tetrasulfonimide or even hexasulfonimide anion.

Typically, in lithium ion battery systems, the positive cation is Li ⁺ , although other metals and non-metal cations may be used as appropriate without adversely affecting the performance of the lithium ion battery. Examples of other cations that can be used with the polyfunctional fluorinated anion of the present invention include, but are not limited to: K ⁺ , Na ⁺ , Mg ²⁺ , Ca ²⁺ , Cu ⁺ , Cu ²⁺ , Zn ²⁺ , Ag ⁺ Various aprotic organic phosphonium cations of Fe ²⁺ , Ni ²⁺ , Au ⁺ , Pt ²⁺ , Co ³⁺ , Al ³⁺ , Mn ³⁺ and N, P, S and O, such as described in US 6,372,829 Nitrogen cation. Typical aprotic organophosphonium cations include quaternary ammonium and quaternary phosphonium cations.

Suitable R _f ' moieties of the disulfonate have from 1 to 10 carbon atoms. In some embodiments, two sulfonate anion having the structure ^{_{- OSO 2 (CF 2) n}} SO 2 O -, where n = 1-10, or even n = 1-4. In other embodiments, two sulfonate anion may be an ^{_{- OSO 2 (CF 2) 3}} SO 2 O - , and ^{_{- OSO 2 (CF 2) 4}} SO 2 O -. The disulfonate anion additive can be added to the electrolyte of the provided lithium ion electrochemical cell in an amount from about 0.01 weight percent to about 3.0 weight percent of the total weight of the electrolyte. In some embodiments, the disulfonate anion additive can be added to the electrolyte in an amount from about 0.1 weight percent to about 1.0 weight percent. In some systems, such as the systems exemplified below, the disulfonate can be only slightly soluble in the other components of the electrolyte. For example, in a solution of 1 M LiPF ₆ in a mixture of ethyl carbonate: ethyl carbonate (3:7 by volume), when 0.5 weight percent of LiOSO ₂ (CF ₂ ) ₃ is added to the solution In the case of SO ₂ OLi, the concentration of the dianion salt was found to be initially 0.09 weight percent, 0.10 weight percent after 30 minutes of stirring, and up to 0.23 weight percent after stirring for 4 hours. The amount of dissolved salt can be readily determined by ¹⁹ F nuclear magnetic resonance (NMR) spectroscopy. The addition of such minor amounts of disulfonated dianion salt to the electrolyte of the provided lithium ion battery can unexpectedly provide resistance to capacity degradation at elevated temperatures (>55 ° C) and high pressures (>4.2 V versus Li/Li ⁺ ). Sex. This effect can be enhanced by adding a small amount of carbonic acid vinyl ester as a co-additive to the electrolyte. Typically, the carbonic acid vinyl ester can be added in an amount from about 0.5 weight percent to about 5.0 weight percent. More typically it can be added in an amount from about 1.5 weight percent to about 2.5 weight percent. In some embodiments, the carbonic acid vinyl ester can be added in an amount of about 2.0 weight percent. In addition, the use of the provided disulfonate anion and its salt can reduce the accumulation of battery impedance at high temperatures and pressures, and improve capacity retention under high temperature storage conditions.

In another embodiment in which X and Y are the same, the polyfunctional anion may be a sulfonimide anion having the formula R _f SO ₂ - ^- N-SO ₂ -R _f '-SO ₂ -N ^- -SO ₂ R _f . Each R _f is a linear or branched fluoroalkyl moiety having 1 to 6 carbon atoms, and R _f ' is a linear or branched or cyclic fluoroalkyl moiety having 1 to 10 carbon atoms. R _f may optionally contain one or more intrachain heteroatoms selected from nitrogen, oxygen or a combination thereof, and the R _f ' moiety may optionally contain one or more intrachain oxygen atoms. Both R _f and R _f ' may be partially fluorinated as appropriate, with up to 20%, up to 10% or even up to 5% of the non-fluorine substituent being hydrogen. In a typical embodiment, all of the _Rf and _Rf ' moieties are perfluorinated.

Some suitable disulfonimide anions have the structure R _f SO ₂ - ^- N-SO ₂ -(CF ₂ ) _n -SO ₂ -N ^- -SO ₂ R _f , where n=1-10 or even n=1 -4. In some embodiments, the disulfonimide anion has the structure R _f SO ₂ - ^- N-SO ₂ -(CF ₂ ) ₄ -SO ₂ -N ^- -SO ₂ R _f . Typically, in lithium ion battery systems, the cation is Li ⁺ , although other metal and non-metal cations may be used as appropriate, as described above. The disulfonimide anion additive can be added to the electrolyte of the provided lithium ion electrochemical cell in an amount from about 0.01 weight percent to about 5.0 weight percent of the total weight of the electrolyte. In some embodiments, the disulfonimide anion additive can be added to the electrolyte in an amount from about 0.1 weight percent to about 2.0 weight percent. Adding such small amounts of the disulfonimide anion salt to the electrolyte of the provided lithium ion battery can unexpectedly provide resistance capacity at high temperatures (>55 ° C) and high pressure (>4.2 V vs. Li/Li ⁺ ). Attenuation. This effect can be enhanced by adding a small amount of carbonic acid vinyl ester as a co-additive to the electrolyte. Typically, the carbonic acid vinyl ester can be added in an amount from about 0.5 weight percent to about 5.0 weight percent. More typically, it can be added in an amount from about 1.5 weight percent to about 2.5 weight percent. In some embodiments, the carbonic acid vinyl ester can be added in an amount of about 2.0 weight percent.

In addition to providing resistance to capacity decay under high temperature and high pressure, the provided disulfonimide anion and its salt can improve the hydrolytic stability of the charged lithium electrolyte salt LiPF ₆ in the electrolyte, and can inhibit HF The resulting HF may be detrimental to the performance of the lithium ion electrochemical cell provided. In addition, the use of the provided disulfonimide anion and its salt can reduce the accumulation of battery resistance at high temperatures and pressures, and improve capacity retention under high temperature storage conditions. Accordingly, a method of stabilizing a lithium ion electrochemical cell comprising adding a provided disulfonimide anion and/or a dilithium salt thereof to an electrolyte of a provided lithium ion electrochemical cell is provided.

Exemplary polyfunctional sulfonate anions useful as additives in the provided lithium ion electrochemical cells include, but are not limited to: ^- O ₃ SCF ₂ SO ₃ ^- , ^- O ₃ SCF ₂ CF ₂ SO ₃ ^- , ^- O ₃ SCF ₂ CF ₂ CF ₂ SO ₃ ^- , ^- O ₃ SCF ₂ CF ₂ CF ₂ CF ₂ SO ₃ ^- , ^- O ₃ SCF ₂ CF ₂ CF ₂ CF ₂ CF ₂ CF ₂ SO ₃ ^- , ^- O ₃ SCF ₂ CF ₂ CF ₂ CF ₂ CF ₂ CF ₂ CF ₂ CF ₂ SO ₃ ^- , ^- O ₃ SCF ₂ CF(CF ₃ )CF ₂ SO ₃ ^- , ^- O ₃ SCF ₂ CF ₂ OCF ₂ CF ₂ SO ₃ ^- ,and .

A polyfunctional sulfonium imine anion useful as an additive in the provided lithium ion electrochemical cell comprises: CF ₃ SO ₂ N( ^- )SO ₂ CF ₂ CF ₂ SO ₂ N( ^- )SO ₂ CF ₃ , CF ₃ SO ₂ N( ^- )SO ₂ CF ₂ CF ₂ CF ₂ CF ₂ SO ₂ N( ^- )SO ₂ CF ₃ , C ₄ F ₉ SO ₂ N( ^- )SO ₂ CF ₂ CF ₂ CF ₂ SO ₂ N ( ^- )SO ₂ C ₄ F ₉ , CF ₃ SO ₂ N( ^- )SO ₂ CF ₂ CF(CF ₃ )CF ₂ SO ₂ N( ^- )SO ₂ CF ₃ , and CF ₃ SO ₂ N( ^- )SO ₂ CF ₂ CF ₂ OCF ₂ CF ₂ SO ₂ N( ^- )SO ₂ CF ₃ .

The electrolyte of the present invention may also include an additive such as a carbonic acid vinyl ester having the structure II wherein R ¹ is H or a C ₁ -C ₄ alkyl or alkenyl group.

Exemplary additives that may be suitable for use in structure (II) of various embodiments of the present invention include, but are not limited to, carbonic acid vinyl ester, methyl methyl carbonate, ethyl vinyl carbonate, vinyl propyl acetate, Isopropylene carbonate, vinyl butyl carbonate, isobutyl vinyl carbonate and the like. Alternatively or additionally, the electrolyte of the present invention may comprise ethyl carbonate, having the structure (III) wherein X ₁ is hydrogen, fluorine or chlorine; and Q is fluorine or chlorine or a C ₁ -C ₄ alkyl or alkenyl group.

Exemplary additives that may be suitable for structure (III) of various embodiments of the present invention include, but are not limited to, fluoroacetate, ethyl chloroacetate, 1,2-difluoroethyl carbonate, carbonate 1 - Fluoro-2-methyl-extended ethyl ester, 1-chloro-2-methyl-extended ethyl carbonate, vinyl ethylene carbonate and the like. Additives such as exemplified by structure (III) may be greater than about 0.5 weight percent (wt%), greater than about 1.0 wt%, greater than about 5 wt%, greater than about 10 wt%, greater than about 20 wt%, greater than the total weight of the electrolyte. Approximately 50 wt% or even greater amounts are added to the electrolyte. Such additives are disclosed, for example, in U.S. Patent Application Publication No. 2009/0053589 (Obrovac et al.).

Other additives, such as a redox chemical shuttle, may also be added to the electrolyte of the provided lithium ion electrochemical cell. The redox chemical shuttle can impart overcharge protection to the rechargeable lithium ion electrochemical cell. The redox chemical shuttles are disclosed, for example, in U.S. Patent No. 7,585,590 (Wang et al.) and U.S. Patent Nos. 7,615,312; 7,615,317; 7, 648, 801; and 7, 811, 710 (all to Dahn et al.). A redox chemical shuttle for a high pressure cathode is disclosed, for example, in U.S. Patent Application Publication No. 2009/0286162 A1 (Lamanna et al.).

The objects and advantages of the present invention are further illustrated by the following examples, but the particular materials and amounts thereof, as well as other conditions and details, are not to be construed as limiting the invention.

Instance Preparation Example 1 - Preparation of LiOSO ₂ (CF ₂ ) ₃ SO ₂ OLi (C3DS).

In a round bottom flask equipped with a mechanical stirrer, thermometer, reflux condenser and addition funnel, 53.091 g of LiOH-H ₂ O (available from FMC Corp., Philadelphia, PA) was dissolved in 275 mL of deionized water. An aqueous solution of LiOH was prepared. Over an hour, 80.00 g of FSO ₂ (CF ₂ ) ₃ SO ₂ F was gradually added from the addition funnel to the stirred 60 ° C LiOH solution (by P. Sartori et al., J. Fluorine Chem ., 83, 145- 149 (1997) and the known electrochemical fluorination process described in U.S. Patent No. 3,476,753 (Hansen). The rate of addition was controlled to avoid heating the reaction mixture to over 85 °C due to exothermic heat of reaction. Once the addition was complete, heating was continued at 80 ° C with stirring for about 3 hours to effect completion of the hydrolysis, followed by cooling the reaction mixture to room temperature. With an excess of dry ice under stirring cooled reaction mixture was treated in the residue is converted to LiOH Li ₂ CO _3. Added under stirring a few grams CELITE (commercially available from Sigma-Aldrich, Milwaukee, WI) and the resultant slurry was filtered by suction to remove insoluble solids (mainly LiF and Li ₂ CO _3). The recovered aqueous filtrate was evaporated to dryness in a pyrex pan by heating at 90 ° C overnight in a convection oven, followed by further drying in a vacuum oven at 20 Torr (2.67 kPa) at 135 °C. The resulting dry salt was dissolved in 200 mL of ethanol (200 proof) and filtered by suction to remove residual Li ₂ CO ₃ and LiF solid. The filtrate was evaporated to dryness on a rotary evaporator at 30 ° C to 80 ° C, 20 Torr to obtain a clear viscous oil. To the oil was added 200 ml of toluene, followed by removal of toluene by rotary evaporation at 50 ° C to 90 ° C, 20 Torr to drive off residual ethanol. The latter process was repeated again to obtain a white solid powder. The solid was transferred to a glass jar and dried overnight at 140 ° C, 10 mTorr (1.3 Pa) in a vacuum oven to remove substantially all of the water and residual volatile organic solvent. A total of 79.1 g of product was recovered (96% yield, based on FSO ₂ (CF ₂ ) ₃ SO ₂ F). The identity and purity of the product was determined by quantitative ¹⁹ F NMR analysis (99.3% LiOSO ₂ (CF ₂ ) ₃ SO ₂ OLi, 0.7% LiOSO ₂ CF ₂ CF(CF ₃ )SO ₂ OLi, 0.02% CF ₃ COOLi, by weight meter).

The solubility of C3DS in the electrolyte solution was measured.

The dissolution kinetics of C3DS in the baseline electrolyte is slow, so it is necessary to know the concentration of C3DS in the electrolyte over time after the initial mixing. The concentration of dissolved C3DS was measured using ¹⁹ F nuclear magnetic resonance spectroscopy. Feed 0.5 wt% C3DS to baseline electrolyte formulation 1.0 M LiPF ₆ ethyl carbonate (EC): ethyl methyl carbonate (EMC) (3:7 by volume) (available from Novolyte, Independence, OH) In solution. The mixture was stirred for 0 minutes (<1 minute), 30 minutes and 4 hours, respectively, in an Ar purge glove work box having a moisture content of less than 5 ppm. An aliquot of the mixture was then filtered and transferred to a sealed NMR tube. NMR samples were analyzed on a Bruker 500 MHz NMR spectrometer. Figure 1 is a ¹⁹ F NMR spectrum of the electrolyte solution after stirring for 4 hours. In Figure 1, the doublet at -74 ppm is produced by the resonance of LiPF ₆ . The peak A at -114 ppm and the peak B at -119 ppm are attributed to the fluorine atoms A and B in the C3DS, respectively.

All peaks of LiOSO ₂ CF ₂ CF ₂ CF ₂ SO ₂ OLi ABA were integrated and normalized for the 1 M LiPF ₆ peak. The peak concentration of peak A and peak B was divided by the peak area of LiPF _{6 to} obtain the molar concentration of C3DS. Assuming that the electrolyte density was 1.17 g/ml, the wt% concentration of C3DS in the electrolyte was easily calculated from the C3DS molar concentration. After stirring for 0 minutes and 30 minutes, the solubility of C3DS was about 0.09 wt% and 0.10 wt%, respectively, and the solubility increased to 0.23 wt% after 4 hours. It should be noted that in the following examples, a lithium ion battery containing a C3DS additive was injected using an electrolyte supernatant solution after stirring a control electrolyte having a C3DS loading of 0.5 wt% for 0 minutes (<1 minute). The C3DS concentration in the electrolyte solution was estimated to be 0.09 wt%.

Preparation Example 2 - Preparation of LiOSO ₂ (CF ₂ ) ₄ SO ₂ OLi (C4DS).

C4DS was prepared using the same procedure as in Preparation Example 1, except that FSO ₂ (CF ₂ ) ₄ SO ₂ F (prepared by electrochemical fluorination as described in Preparation Example 1) was used as a starting material. The product was isolated and its identity and purity (99.210% LiO ₃ S(CF ₂ ) ₄ SO ₃ Li by weight) was determined by ¹⁹ F NMR analysis.

Preparation Example 3 - Preparation of (Li ⁺ ) ₂ [CF ₃ SO ₂ NSO ₂ (CF ₂ ) ₄ SO ₂ NSO ₂ CF ₃ ] ^2- (C4DI).

Bifunctional imidic acid CF ₃ SO ₂ NHSO ₂ (CF ₂ ) ₄ SO ₂ NHSO ₂ CF _{3 in the} form of the tetrahydrate is prepared according to the procedure described in U.S. Patent No. 7,517,604, column 10, line 40. 500 mL with a magnetic stir bar, heating mantle, Claisen adapter, thermocouple probe, addition funnel and Dean-Stark trap with water-cooled condenser This material (66.7 g) was fed into a 2-neck round bottom flask. Deionized water (16.7 mL) was added with stirring at room temperature to dissolve the difunctional phthalimidic acid. Subsequently, 6.55 g of LiOH-H ₂ O was added with stirring to partially neutralize the acid. Once the exotherm subsided, 1.71 g of Li ₂ CO _{3 was added} to complete the neutralization. Once the foaming (due to the precipitation of CO ₂ ) subsided, the reaction mixture was heated to 70 ° C to 80 ° C with stirring. Next, 9.0 mL of a 50% aqueous H ₂ O ₂ solution was added dropwise with stirring to bleach the brown color caused by a small amount of impurities. Once all of the hydrogen peroxide has been added, the reaction temperature is maintained at 80 ° C for one hour with stirring to complete the bleaching process. Once the bleaching is complete, the reaction temperature is raised to distill the water. A total of 12 mL of water was collected in a Dean Stark trap and discarded to concentrate the dilithium salt remaining in the tank to about 80% solids. After cooling the concentrate to room temperature, the dilithium salt remains dissolved in the aqueous solution. The clear, colorless filtrate, pH 7.0, was obtained by suction filtration of the concentrate through a 0.2 micron GHP membrane (available from Pall Life Sciences, Port Washington, NY) to remove excess undissolved lithium carbonate. The filtrate was transferred to a Peuge's crystallizing dish and partially dried at 160 ° C in a convection oven to form a white solid. The white solid was transferred to a glass jar and further dried overnight at 150 ° C, 0.01 torr (Torr) in a vacuum oven. Immediately after cooling to near room temperature in vacuo, the pure white powder product was transferred to a dry box under nitrogen for storage and sampling. The isolated yield of (Li ⁺ ) ₂ [CF ₃ SO ₂ NSO ₂ (CF ₂ ) ₄ SO ₂ NSO ₂ CF ₃ ] ^2- (C4DI) was 59.45 g (96.8% yield). Quantitative ¹⁹ F NMR analysis confirmed the structure of the product to a purity of 97.2 wt%.

Electrochemical cell preparation.

Preparation of electrodes

95% by weight of LiNi _0.4 Mn _0.4 Co _0.2 O ₂ (positive electrode active material, available from 3M, St. Paul, MN), 2.5% by weight of Super P (Super P) carbon (conductive agent, available from Timcal Graphite and Carbon, Bodio, Switzerland) and 2.5% by weight of polyvinylidene fluoride adhesive (KYNAR RX PVDF, available from Arkema Inc., King of Prussia, PA) in 1-methyl-2-pyrrole as solvent The ketone (NMP, available from Honeywell) was mixed. The above solution had a solid content of 58.3 wt% and a slurry wet density of 1.91 g/cm ³ . The resulting slurry was then coated on an aluminum foil and dried at 120 ° C to prepare a positive electrode (cathode). The resulting cathode was then calendered to 2.91 g/cm ³ (30% porosity) prior to use. Similarly, 92% by weight of MAGE graphite (negative electrode active material, available from Hitachi) and 8% by weight of PAA-Li binder (from PAA (polyacrylic acid, available from Sigma-Aldrich) by using an aqueous solution of LiOH Prepared by neutralization) mixed in water as a solvent. The resulting mixture was coated on a copper foil and dried to form a negative electrode. The anode was calendered to 1.61 g/cm ³ (25% porosity) prior to battery assembly.

Preparation of electrolyte

A non-aqueous solvent mixture comprising ethylene carbonate (EC): ethyl carbonate (EMC) (both available from Novolyte) in a ratio of 3:7 by volume was prepared. A lithium salt LiPF ₆ (commercially available from Novolyte) was dissolved in the above solvent mixture to prepare a 1.0 M electrolyte stock solution. Various amounts of additives were added to the 1.0 M electrolyte solution as indicated in the examples below. All electrolytes were prepared in an Ar purge glove work box with a water content of less than 5 ppm. The above formulated electrolyte is filtered just prior to injection into the lithium ion battery.

Preparation of coin type battery

A coin-type battery was assembled in a stainless steel coin-type battery hardware of 2325 size (diameter 23 mm and thickness 2.5 mm) using the obtained cathode and anode in a drying chamber. Two layers of CELGARD #2335 (available from Celgard Charlotte, NC) were used as the separator. 100 μl of the electrolyte prepared as described above was manually injected into the coin type battery. Finally, the battery is sealed by crimping.

Coin battery cycle

Coin-type battery test conditions (voltage limits, temperature, and rate) were chosen to stress the cell and cause significant capacity decay of the control cell after 200 cycles of cycling to allow for distinguishable use of additives and no use of additives. efficacy. Additive testing was performed at two different temperatures (room temperature and 60 °C) using the test protocol described below. For any given battery, form And the circulation system is carried out at the same temperature.

1) Standard formation step (charging with C/8 constant current to 4.4 V, constant voltage trickle to C/30 limit - static for 15 minutes at open circuit voltage - discharge to 2.5 at C/8 constant current) V- is at rest for 15 minutes at open circuit voltage).

2) Charge at a constant current of C/2 to 4.4 V, and charge the constant voltage to the C/20 limit.

3) Discharge at a constant current of 1 C to 2.5 V - stand still for 15 minutes at open circuit voltage.

4) Steps 2 through 3 are repeated for another 200 cycles.

Comparative Example 1 and Comparative Example 2 and Example 1 and Example 2

A coin type battery was prepared using the cathode and the anode as described above. The additives shown in Table 1 were added to the above prepared electrolyte stock solution containing 1.0 M LiPF ₆ .

The coin type batteries of Comparative Example 1 to Comparative Example 2 and Examples 1 to 2 were compared according to the scheme detailed above. Different batches of batteries were circulated at room temperature and at 60 ° C (high temperature). Figure 2a includes a plot of discharge specific capacity (mAh/g) versus cycle number for a coin-type battery for a coin-type battery maintained at room temperature. The battery with the addition of VC (Comparative Example 2) and the combination of VC and C3DS (Example 2) showed significant capacity decay after 100 cycles when circulating at room temperature. However, the control cells and the C3DS cells (Comparative Example 1 and Example 1) convey similar recyclability with no significant capacity loss after 200 cycles.

As shown in Figure 2b, the C3DS-containing cell (Example 1) showed higher discharge capacity retention compared to the control cell (Comparative Example 1) under more extreme conditions (60 °C cycle). The VC+C3DS binary mixture (Example 2) provided even better cycle performance compared to VC alone (Comparative Example 2) at 60 °C.

Comparative Example 3 and Comparative Example 4 and Example 3 and Example 4

A coin type battery was prepared using the cathode and the anode as described above. A non-aqueous solvent mixture comprising EC:EMC in a ratio of 3:7 by volume was prepared. A lithium salt LiPF _{6 was} dissolved in the above solvent mixture to prepare a 1.0 M electrolyte stock solution. The additives shown in Table 2 were added to the above 1.0 M LiPF ₆ electrolyte stock solution. A mixture of 2.0 wt% of vinyl carbonate (VC), 2.0 wt% of C4DI, and 2.0 wt% of VC + 2.0 wt% C4DI was added to separate samples of the baseline (or control) electrolyte solution, respectively. All electrolytes were prepared in an Ar purge glove work box with a water content of less than 5 ppm.

A positive electrode containing a lithium mixed metal oxide, 95% by weight of LiNi _0.4 Mn _0.4 Co _0.2 O ₂ and a MAGE graphite anode was prepared as described in Examples 1 to 2 above.

A coin type battery is assembled as described above. The coin-type battery test conditions (voltage limit, temperature, and rate) were selected to subject the battery to pressure, and significant capacity decay occurred after the control battery was subjected to 200 cycles to distinguish between the presence of additives and the absence of additives. Under the performance. Additive testing was performed using the same test protocol as Examples 1 through 2 above at two different temperatures (room temperature and 60 °C). For any given battery, the formation and cycling are performed at the same temperature.

Fig. 3 is a graph showing the relationship between the discharge capacity of the coin battery and the number of cycles under extreme conditions (60 ° C cycle). The cell containing the C4DI additive showed a higher discharge capacity retention compared to the control cell (without the additive). At 60 ° C, a battery containing a VC+C4DI binary additive mixture provides even better cycle life performance compared to VC or C4DI addition alone.

Comparative Example 5 and Comparative Example 6 and Example 5 and Example 6

In Examples 5 to 6 and Comparative Example 5 to Comparative Example 6, coin type batteries were constructed in the same manner as Examples 1 to 2 and Comparative Example 1 to Comparative Example 2, except that high pressure LiMn _1.5 was used in the coin type battery. Ni _0.5 O ₄ spinel cathode. A positive electrode containing a high pressure spinel LiMn _1.5 Ni _0.5 O ₄ cathode material was prepared using a solid state method. The precursor powders NiO, Mn ₂ O ₃ , and Li ₂ O are mixed together by a combination of roll grinding and automatic grinding. The material is then sintered in an oven having a temperature profile of 900 °C to 750 °C. After cooling, the material was gently ground and sieved at 100 microns. Subsequently, LiMn _1.5 Ni _0.5 O ₄ powder was mixed with PVDF, NMP and Super P in a Mazerustar mixer to produce a 90:5:5 coating slurry. The slurry was coated on an aluminum foil and dried under vacuum at 120 ° C for use as a cathode in the following 5 V cycle study.

The effectiveness of C4DI additives in higher voltage Li-ion battery chemistry was investigated by cycling in a MAGE graphite/LiMn _1.5 Ni _0.5 O ₄ coin cell. The battery was cycled between 4.9 V and 2.5 V at room temperature with a C/2 charge and discharge rate. The baseline (control) electrolyte was 1 M LiPF ₆ EC: EMC (3:7 by volume) solution (Comparative Example 5). The electrolyte of the present invention was prepared by adding 0.5 wt% C4DI (Example 5) and 2.0 wt% C4DI (Example 6) to the baseline electrolyte. A comparative example containing a baseline electrolyte with 2.0 wt% VC added (Comparative Example 6) was also included. Figure 4 shows the relationship between the discharge capacity of these batteries and the number of cycles. It is apparent that the addition of 0.5 wt% and 2.0 wt% C4DI to the baseline electrolyte significantly improved the high pressure compared to the control cell without the additive (Comparative Example 5) or the battery containing 2.0 wt% VC (Comparative Example 6). The discharge capacity of the MAGE graphite/LiMn _1.5 Ni _0.5 O ₄ battery was maintained.

Thermal storage test of coin-type battery with LiNi _0.4 Mn _0.4 Co _0.2 O ₂ cathode

Electrolyte with LiNi _0.4 Mn _0.4 Co _0.2 O ₂ cathode, MAGE graphite anode and no additive, electrolyte containing 2% ethylene carbonate extended ethylene ester, containing 0.5% HQ-115 (comparative fluorinated electrolyte additive, available for purchase) An electrolyte from 3M, St. Paul, MN), an electrolyte containing 0.09% C3DS, an electrolyte containing 0.09% C4DS, and an electrolyte containing 0.5% by weight of C4DI additive at room temperature at a C/10 rate of 4.2 Charge and discharge seven times between V and 2.8 V. The battery is then charged to a terminal voltage of 4.2 V at 100% state of charge (SOC). All coin cells were then stored in a 60 ° C oven for one week. The battery was then discharged and charged four times at room temperature. The discharge capacity of the battery before and after the heat storage was collected and the irreversible capacity loss (IRC) of the battery was calculated based on the schematic diagram of FIG. Figure 6 clearly shows that the C3DS, C4DS and C4DI additions reduce the irreversible capacity loss of batteries stored at elevated temperatures compared to the control without the additive. The degree of improvement in performance obtained with 0.09 wt% C3DS, 0.09 wt% C4DS, and 0.5 wt% C4DI is comparable to that obtained with a significantly higher loading of vinyl carbonate extender (2.0 wt%) and is superior to use. The degree of improvement in performance obtained by 0.5 wt% HQ-115.

Inhibition of harmful effects on water pollution in coin-type batteries containing C4DI additives

To determine the effect of C4DI additives on the performance of coin-type batteries when a known amount of water is present, batteries containing baseline electrolyte and electrolyte with 2.0 wt% C4DI are injected at 1000 ppm water (in electrolyte) at room temperature Cycles between 4.2 V and 2.8 V at a C/5 rate. Figure 7 shows the discharge specific capacity of these batteries in relation to the number of cycles. The addition of 2.0 wt% C4DI greatly improved the discharge capacity of a lithium ion battery containing 1000 ppm of water and reduced its impedance.

Hydrolytic stability and thermal stability of LiPF ₆ based electrolyte containing C4DI additives

¹ H and ¹⁹ F NMR spectroscopy were used to determine whether C4DI significantly improved the hydrolytic stability of LiPF ₆ and inhibited HF production when water contamination was present in the LiPF ₆ containing electrolyte. First, 2.0 wt% C4DI was fed into the base electrolyte formulation 1 M LiPF ₆ EC: EMC (3:7 by volume). Next, 300 ppm deionized water was separately added to the baseline electrolyte sample and the electrolyte sample containing 2.0 wt% C4DI in a drying chamber having a dew point of less than -70 °C. After storage in plastic bottles for 24 hours at room temperature, each solution was transferred to a sealed NMR tube. NMR samples were analyzed on a Bruker 500 MHz NMR spectrometer. In the ¹ H NMR spectrum of the baseline electrolyte, the doublet at 7.8 ppm was generated by the proton resonance of HF. Similarly, in the ¹⁹ F NMR spectrum of the baseline electrolyte, HF was also identified as a double peak at -189 ppm (split due to HF coupling). In the ¹⁹ F NMR spectrum of the baseline electrolyte, the fluorophosphate OPF ₂ OH was also identified as a double peak at -88 ppm. Interestingly, in the electrolyte containing 2.0 wt% C4DI addition, no HF and OPF ₂ OH signals were observed, thereby indicating that C4DI inhibited LiPF ₆ hydrolysis and associated HF production. It is expected that HF production is inhibited by the stability of the electrolyte by limiting acid-induced electrolyte solvent decomposition on the electrode surface and reducing unwanted acid-induced reactions.

To better quantify the ability of 2.0 wt% C4DI additives to inhibit HF production, different concentrations of water were separately added to the baseline electrolyte and 2.0 wt% C4DI electrolyte using the protocol described above. After storage at room temperature for 24 hours, a ¹⁹ F NMR spectrum of a baseline electrolyte with 300 ppm, 500 ppm, 700 ppm, and 1000 ppm water and a 2.0 wt% C4DI electrolyte solution was obtained. The results show that 2 wt% C4DI prevents detectable amounts of HF formation even after adding up to 1000 ppm water to the LiPF ₆ -based electrolyte.

The following is an illustrative embodiment of a lithium ion electrochemical cell comprising a fluorinated carbon electrolyte additive of the present invention.

Embodiment 1 is a lithium ion electrochemical battery comprising: a positive electrode comprising a lithium metal oxide or a lithium metal phosphate; a negative electrode capable of intercalating lithium or forming an alloy with lithium; and a liquid or gel electrolyte containing the additive Wherein the additive comprises a polyfunctional anion having the formula: X-SO ₂ -R _f '-SO ₂ -Y, wherein X and Y are independently O ^- or R _f SO ₂ N ^- , wherein R _f is a linear or branched fluoroalkyl moiety of 1 to 6 carbon atoms and optionally one or more interchain heteroatoms selected from nitrogen, oxygen or a combination thereof, wherein R _f 'is from 1 to 10 carbon atoms A straight or branched chain or cyclic fluoroalkyl group optionally containing one or more intrachain oxygen atoms, and wherein both R _f and R _f ' have up to 20% non-fluorine substituents.

Embodiment 2 is the lithium ion electrochemical cell of embodiment 1, wherein the positive electrode comprises a lithium metal oxide.

Embodiment 3 is the lithium ion electrochemical cell of embodiment 2, wherein the lithium metal oxide comprises a lithium mixed metal oxide comprising cobalt, nickel, manganese, or a combination thereof.

Example 4 Example 1 are as lithium-ion electrochemical cell of the embodiment, wherein the multi-functional anion having the formula of ^{_{dianion: - OSO 2 (CF 2)}} n SO 2 O -, where n = 1-10.

Embodiment 5 is a lithium ion electrochemical cell as in Example 4, wherein the n = 1-4.

Embodiment 6 is the lithium ion electrochemical cell of embodiment 4, wherein the additive is present in an amount from about 0.1 weight percent to about 1.0 weight percent of the total weight of the electrolyte.

Embodiment 7 is a lithium ion electrochemical cell as in Example 1, wherein X is the same as Y.

Embodiment 8 is the lithium ion electrochemical cell of embodiment 1, wherein the additive comprises at least one lithium ion.

Embodiment 9 is the lithium ion electrochemical cell of embodiment 1, further comprising a charged medium and an electrolyte salt.

Embodiment 10 is the lithium ion electrochemical cell of embodiment 9, wherein the charged medium comprises an organic carbonate.

Embodiment 11 is the lithium ion electrochemical battery of embodiment 10, wherein the organic carbonate comprises ethyl carbonate, dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate, ethylene carbonate, and carbonic acid 2- Fluoride ethyl ester or a combination thereof.

Embodiment 12 is the lithium ion electrochemical cell of embodiment 11, wherein the organic carbonate comprises a carbonic acid vinyl ester.

Embodiment 13 is the lithium ion electrochemical cell of embodiment 9, wherein the electrolyte salt is selected from the group consisting of LiPF ₆ , LiBF ₄ , LiClO ₄ , lithium bis(oxalate) borate, LiN(SO ₂ CF ₃ ) ₂ , LiN (SO) ₂ C ₂ F ₅ ) ₂ , LiAsF ₆ , LiC(SO ₂ CF ₃ ) ₃ , LiN(SO ₂ F) ₂ , LiN(SO ₂ F)(SO ₂ CF ₃ ), LiN(SO ₂ F)(SO ₂ C ₄ F ₉ ) and combinations thereof.

Embodiment 14 is the lithium ion electrochemical cell of embodiment 13, wherein the electrolyte salt comprises LiPF ₆ or lithium bis(oxalate) borate.

Embodiment 15 is the lithium ion electrochemical cell of embodiment 14, wherein the electrolyte further comprises a carbonic acid vinyl ester.

Embodiment 16 is the lithium ion electrochemical cell of embodiment 1, wherein the dianion has the chemical formula: R _f SO ₂ -N ^- -SO ₂ -(CF ₂ ) _n -SO ₂ -N ^- -SO ₂ R _f .

Embodiment 17 is the lithium ion electrochemical cell of embodiment 16, wherein the additive is present in an amount from about 0.5 weight percent to about 4.0 weight percent of the total weight of the electrolyte.

Embodiment 18 is the lithium ion electrochemical cell of embodiment 16, wherein the electrolyte further comprises a carbonic acid vinyl ester.

Embodiment 19 is the lithium ion electrochemical cell of embodiment 1, wherein the additive is perfluorinated.

Embodiment 20 is a method for stabilizing a lithium ion electrochemical cell, comprising: providing a lithium having a lithium metal oxide positive electrode or a lithium metal phosphate positive electrode, a negative electrode capable of intercalating lithium or forming an alloy with lithium, and a liquid electrolyte An ion electrochemical cell to which a polyfunctional anion having the formula: X-SO ₂ -R _f '-SO ₂ -Y is added, wherein X and Y are independently O ^- or R _f SO ₂ N ^- , wherein R _f is a linear or branched fluoroalkyl moiety of 1 to 6 carbon atoms and optionally one or more intrachain heteroatoms selected from the group consisting of oxygen, nitrogen or a combination thereof, wherein R _f 'is from 1 to 10 carbon atoms A straight or branched chain or cyclic fluoroalkyl group optionally containing one or more intrachain oxygen atoms, and wherein both R _f and R _f ' have up to 20% non-fluorine substituents.

Embodiment 21 is the method of stabilizing a lithium ion electrochemical cell according to embodiment 20, wherein X and Y are R _f SO ₂ N ^- , and wherein the amount of the divalent anion added to the electrolyte is about the total weight of the electrolyte From 0.05 weight percent to about 3.0 weight percent.

Embodiment 22 is a lithium ion electrochemical battery comprising: a positive electrode comprising a lithium metal oxide or a lithium metal phosphate; a negative electrode capable of intercalating lithium or forming an alloy with lithium; and a solid polymer electrolyte comprising an additive, Wherein the additive comprises a polyfunctional anion having the formula: R _f SO ₂ -N ^- -SO ₂ -(CF ₂ ) _n -SO ₂ -N ^- -SO ₂ R _f , wherein R _f is from 1 to 6 The linear or branched fluoroalkyl portion of a carbon atom and optionally contains one or more intrachain heteroatoms selected from the group consisting of nitrogen, oxygen, or combinations thereof, wherein _Rf has up to 20% non-fluorine substituents.

Embodiment 23 is a lithium ion electrochemical battery comprising: a positive electrode comprising a lithium metal oxide or a lithium metal phosphate; a negative electrode capable of intercalating lithium or forming an alloy with lithium; and a solid electrolyte comprising an additive, wherein additives having the formula comprising many functional ^{_{anions: - O-SO 2 -R f}} '-SO 2 -O -, wherein R _f' is an alkylene group and having a branched or cyclic fluoro 1-10 carbon atoms Optionally, one or more intrachain oxygen atoms are present, and wherein _Rf ' has up to 20% non-fluorine substituents.

It will be apparent to those skilled in the art that various modifications and changes can be made in the present invention without departing from the scope and spirit of the invention. It is to be understood that the invention is not intended to be limited by the illustrative embodiments and examples set forth herein, and such examples and examples are presented by way of example only, and the scope of the invention is intended to be Patent scope restrictions. All references cited in the present invention are hereby incorporated by reference in their entirety.

Figure 1 is a disulfonate of Preparation Example 1 by reacting 1.0 M LiPF ₆ of ethyl carbonate (EC): ethyl carbonate (EMC) (3:7 by volume) solution electrolyte with 0.5 wt% In combination, a ¹⁹ F NMR spectrum of the supernatant solution was obtained after stirring at room temperature for 1 minute.

2a and 2b are graphs showing the relationship between the discharge specific capacity (mAh/g) and the number of cycles of an exemplary coin type battery and a comparative coin type battery containing a C3DS additive at room temperature and at 60 ° C, respectively.

Fig. 3 is a graph showing the relationship between the normalized capacity retention and the number of cycles of an exemplary coin type battery and a comparative coin type battery containing a C4DI additive at 60 °C.

4 is a graph showing the relationship between the discharge specific capacity (mAh/g) and the number of cycles of an exemplary coin type battery and a comparative coin type battery having a C4DI additive and a high pressure LiMn _1.5 Ni _0.5 O ₄ spinel cathode.

Figure 5 is a schematic diagram showing how the irreversible capacity loss percentage is calculated from the high temperature heat storage data in the full battery.

Figure 6 is a bar graph of the irreversible capacity loss of an exemplary coin type battery and a comparative coin type battery after storage.

Figure 7 is a graph showing the discharge specific capacity (mAh/g) versus cycle number for an electrochemical cell and a comparative electrochemical cell provided with 0.1 weight percent water added.

Claims (23)

A lithium ion electrochemical battery comprising: a positive electrode comprising a lithium metal oxide or a lithium metal phosphate; a negative electrode capable of intercalating lithium or forming an alloy with lithium; and a liquid or gel electrolyte containing an additive, wherein the addition The substance comprises a polyfunctional anion having the formula: X-SO ₂ -R _f '-SO ₂ -Y, wherein X and Y are independently O ^- or R _f SO ₂ N ^- , wherein R _f is from 1 to 6 a linear or branched fluoroalkyl moiety of a carbon atom and optionally one or more interchain heteroatoms selected from nitrogen, oxygen or a combination thereof, wherein R _f ' is a straight chain having from 1 to 10 carbon atoms or Branched or cyclic fluoroalkyl and optionally contains one or more intrachain oxygen atoms, and wherein both _Rf and _Rf ' have up to 20% non-fluorine substituents. A lithium ion electrochemical cell according to claim 1 wherein the positive electrode comprises a lithium metal oxide. A lithium ion electrochemical cell according to claim 2, wherein the lithium metal oxide comprises a lithium mixed metal oxide comprising cobalt, nickel, manganese or a combination thereof. The requested item of a lithium-ion electrochemical cell, wherein the multi-functional anion having the formula of ^{_{dianion: - OSO 2 (CF 2)}} n SO 2 O -, where n = 1-10. A lithium ion electrochemical cell according to claim 4, wherein the n = 1-4. A lithium ion electrochemical cell according to claim 4, wherein the additive is The total weight of the electrolyte is present in an amount from about 0.1 weight percent to about 1.0 weight percent. A lithium ion electrochemical cell according to claim 1 wherein X is the same as Y. A lithium ion electrochemical cell according to claim 1 wherein the additive comprises at least one lithium ion. A lithium ion electrochemical cell according to claim 1, which further comprises a charged medium and an electrolyte salt. A lithium ion electrochemical cell according to claim 9 wherein the charged medium comprises an organic carbonate. A lithium ion electrochemical cell according to claim 10, wherein the organic carbonate comprises ethyl carbonate, ethyl dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate, ethylene carbonate, and 2-fluoroethyl carbonate. Or a combination thereof. A lithium ion electrochemical cell according to claim 11 wherein the organic carbonate comprises a vinyl carbonate. A lithium ion electrochemical cell according to claim 9, wherein the electrolyte salt is selected from the group consisting of LiPF ₆ , LiBF ₄ , LiClO ₄ , lithium bis(oxalate) borate, LiN(SO ₂ CF ₃ ) ₂ , LiN (SO ₂ C ₂ F ₅ ) ₂ , LiAsF ₆ , LiC(SO ₂ CF ₃ ) ₃ , LiN(SO ₂ F) ₂ , LiN(SO ₂ F)(SO ₂ CF ₃ ), LiN(SO ₂ F)(SO ₂ C ₄ F ₉ ) and its combination. A lithium ion electrochemical cell according to claim 13 wherein the electrolyte salt comprises LiPF ₆ or lithium bis(oxalate) borate. A lithium ion electrochemical cell according to claim 14 wherein the electrolyte further comprises carbonic acid extending vinyl ester. A lithium ion electrochemical cell according to claim 1, wherein the divalent anion has the chemical formula: R _f SO ₂ -N ^- -SO ₂ -(CF ₂ ) _n -SO ₂ -N ^- -SO ₂ R _f . The lithium ion electrochemical cell of claim 16, wherein the additive is present in an amount from about 0.5 weight percent to about 4.0 weight percent of the total weight of the electrolyte. A lithium ion electrochemical cell according to claim 16 wherein the electrolyte further comprises carbonic acid extending vinyl ester. A lithium ion electrochemical cell according to claim 1 wherein the additive is perfluorinated. A method for stabilizing a lithium ion electrochemical cell, comprising: providing a lithium ion electrochemical cell having a lithium metal oxide positive electrode or a lithium metal phosphate positive electrode, a negative electrode capable of intercalating lithium or forming an alloy with lithium, and a liquid electrolyte , adding a polyfunctional anion having the formula: X-SO ₂ -R _f '-SO ₂ -Y, wherein X and Y are independently O ^- or R _f SO ₂ N ^- , wherein R _f is from 1 to 6 a linear or branched fluoroalkyl moiety of a carbon atom and optionally one or more interchain heteroatoms selected from the group consisting of oxygen, nitrogen, or a combination thereof, wherein R _f ' is a straight chain having from 1 to 10 carbon atoms or Branched or cyclic fluoroalkyl and optionally contains one or more intrachain oxygen atoms, and wherein both _Rf and _Rf ' have up to 20% non-fluorine substituents. A method of stabilizing a lithium ion electrochemical cell according to claim 20, wherein X and Y are R _f SO ₂ N ^- , and wherein the amount of the dianion added to the electrolyte is about 0.05% by weight based on the total weight of the electrolyte Up to about 3.0 weight percent. A lithium ion electrochemical battery comprising: a positive electrode comprising a lithium metal oxide or a lithium metal phosphate; a negative electrode capable of intercalating lithium or forming an alloy with lithium; and a solid polymer electrolyte comprising an additive, wherein the additive A polyfunctional anion having the formula: R _f SO ₂ -N ^- -SO ₂ -(CF ₂ ) _n -SO ₂ -N ^- -SO ₂ R _f , wherein R _f is straight from 1 to 6 carbon atoms The chain or branched chain fluoroalkyl moiety and optionally contains one or more intrachain heteroatoms selected from the group consisting of nitrogen, oxygen, or combinations thereof, wherein _Rf has up to 20% non-fluorine substituents. A lithium ion electrochemical battery comprising: a positive electrode comprising a lithium metal oxide or a lithium metal phosphate; a negative electrode capable of intercalating lithium or forming an alloy with lithium; and a solid electrolyte comprising an additive, wherein the additive comprises a polyfunctional anion of the formula: ^- O-SO ₂ -R _f '-SO ₂ -O ^- , wherein R _f 'is a branched or cyclic fluoroalkyl group having from 1 to 10 carbon atoms and optionally contains one Or a plurality of intrachain oxygen atoms, and wherein _Rf ' has up to 20% non-fluorine substituents.